1. Field of the Invention
The present invention generally relates to a computer based re-work shop order scheduling system on the manufacturing shop floor and, more particularly, to a system which automatically interfaces a production dispatch system and a production planning system to provide an integrated approach to a manufacturing software design. The invention provides an easy to use, user friendly interface for the shop foreman to schedule re-work orders along with regular orders in the most efficient way, considering possible production stoppages for other existing shop orders. This invention deals with re-work shop orders, whereas the above-referenced copending application deals with releasable orders for dispatch on the shop floor.
2. Description of the Prior Art
The process of designing, developing and manufacturing a new product, or making major changes to existing products, presents many challenges to product managers and manufacturing managers to bring a product to market for the least cost, within schedule, while maintaining product quality. In today's highly competitive industries, product managers and manufacturing managers require information to address many problems that arise because of the complexity of new products and the complexity of world-wide production and the changing nature of competition. The requirement that products be manufactured for the least possible cost is important in all industries. Of all the costs associated with selling products and services, none is more important than the cost of customer service. When customers require items to be reworked, or field returns, those orders require special attention and sometimes urgent attention which compete for resources on the shop floor with regular orders. The requirement that products be manufactured in as short a period as possible while maintaining a low level of inventory on the shop floor to meet customer needs presents conflicting criteria to be analyzed in order to make timely decisions.
Many authors have written books in the field of production management. For example, Joseph Orlicky wrote Material Requirement Planning, published by McGraw-Hill, which has become the industry standard reference for almost all job shop planning requirements. This concept of planning and releasing work to the manufacturing shop floor is well accepted and, even today, many vendors are selling software based on the concept. From a dispatching point of view, this system takes into account only the general concept of first-in, first-out (FIFO) basis of dispatching. Dr. D. T. Phillips and G. L. Hogg published a paper entitled "A State-of-the-Art Survey of Dispatching Rules for Manufacturing Shop Operation", International Journal of Production Research, vol. 20, no. 1, pp. 27-45, which provides varying dispatching rules that can be used in a planning process. The International Business Machines (IBM) Corp. has a product called "Capacity Planning and Operation Sequencing System (CAPOSS)", described in education guide No. SR19-5004-0 published by IBM, that provides static dispatching functions in the form of deciding the next operation to be performed for an order after completion of a prior operation. This product provides the capability to change a dispatching process that is pre-assigned to another process. The limitation with this approach is that the system does not analyze the impact of a change to another operation. The system just provides the capability to change the operation and does not analyze the operational dynamics of one order affecting another in the downstream process.
What is needed is an expert system that is simple to use and is user friendly to analyze the dispatch decisions to be made and recommends the alternatives based on a given criteria; e.g., reduce the number of late orders or maximize throughput while accommodating for re-work orders received during the execution process.
Expert systems are a branch of computer science, generally referred to as artificial intelligence, which exhibits characteristics normally associated with human behavior including learning, reasoning, solving problems and so forth. More specifically, an expert system or "knowledge based" system uses certain rules and a database to provide a user interactive environment in the form of a "consultation dialogue", just as a user would interact with a human expert.